Moth caterpillars and many other insect larvae spin silk coverings for the chrysalis. These silk casings are called cocoons. Cocoons can be soft or hard, solid or web-like and any of several different colors or even see-through.

Cocoons provide camouflage and additional protection for the chrysalis. Many moth caterpillars will spin their cocoons in concealed locations, such as the underside of leaves, at the base of a tree, or hanging from a small branch.

While some people think of cocoons as a resting place, there's no resting going on inside the cocoon! To the contrary, there's a lot of activity. Inside the cocoon and the chrysalis, the caterpillar is transforming into a new creature. This requires that the old caterpillar body be broken down and turned into something new. Think of it as insect recycling!

Inside a chrysalis, a caterpillar's body digests itself from the inside out. The same juices it used to digest food as a larva it now uses to break down its own body!

The process of transformation within the chrysalis is known as holometabolism. Although it varies by species, the whole process usually takes about two weeks. In some species, though, the process can take months if they stay inside the chrysalis to survive cold winter weather.

Insects that spin cocoons must eventually escape from them to complete their transformation. Some escape by cutting their way out from the inside. Others may secrete fluids that soften the cocoon and make it easier to escape.

Wonder What's Next?

Tomorrow’s Wonder of the Day takes a trip to one of our favorite places!

Try It Out

Grab a friend or family member and explore one or more of the transformational activities below to help extend your learning about butterflies:

Ever feel like crawling up in your own life-size cocoon? On cool nights, it can be fun to wrap yourself in several blankets when it's time for bed. It can also be fun to pretend that years and years have passed while you've been resting in your cocoon. Grab a friend or family member and some sleeping bags or blankets. Have them help you build your own personal cocoon. Crawl inside with a notebook and a pen and pretend that you're in the cocoon for about five years. Take some notes as you think about these questions:

Share your thoughts with your friends and family members. What do they think the world will be like five years from now? Would they want to take a nap and wake up five years later? Why or why not? What would you miss the most during that time? Have fun using your imagination in your homemade cocoon!

Feeling crafty? Try out this fun arts and crafts project that helps you turn what you learned today into an artistic outlet for your creativity!

Wonderopolis

Noel

Jun 25, 2016

OK one day I noticed a caterpillar on one of my tall plants in my backyard. I noticed each day that it was climbing a little higher and higher until it finally turned upside down and formed a cocoon. But this cocoon wasn't like any I'd ever seen pictures of and I thought that something must have gone wrong and it died. But I was wrong because about a week later it opened up and four more very small caterpillars that looked identical to the first one were all of sudden hanging out on the stems nearby! And now two of those have made cocoons that look just like the first one and a third is in the process of getting ready to go into its own cocoon as Well! I've looked everywhere on the Internet to find something about this. But everything I read tells me that after the cocoon comes the butterfly!. But that's not what is happening here and I can't find any info on this anywhere!. My friends and I are starting to think I've found an alien bug! Really...we just have no explanation for it and I have documented each stage on my phones camera and video. Can you explain to me that this is possible and it's not a new species or something? I can send pictures if you'd like. Thank You! I can't wait to hear from you!

Wonderopolis

Jun 28, 2016

That sounds very interesting, Noel! We are not sure what type of insect you saw. You may want to visit your local library to find books about insects that build cocoons -- perhaps the answer is in there! Or is there a biology/science teacher you could ask? :)

Wonderopolis

May 15, 2014

Great questions from Mrs. Gill's students! The butterfly is a butterfly once it leaves the cocoon. The butterfly in the video is a black swallowtail butterfly. Thanks for WONDERing with us today, Wonder Friends! :-)

Wonderopolis

Julie

May 24, 2013

This wonder is awesome! When I was in 2nd grade our teacher kept caterpillars in the classroom. We got to see them transform into butterflies! We also got to see silk worms turn into moths in 2nd grade also! The caterpillar's cocoon is actually called a chysallis. The silkworm's cocoon is called a cocoon. :lol:

Wonderopolis

May 24, 2013

What an awesome connection to our growing Wonder, Julie! Nice work! It sounds like you've seen this Wonder up close and personal in 2nd grade- how neat! We loved learning about that cool experience in your classroom and we appreciate all the WONDERful facts you have shared today! If you could be any type of insect, what would it be? :)

Wonderopolis

Apr 18, 2013

HOORAY! Thank you for sharing your awesome comment with us today, Wonder Friends in Mr. Johnson's Class! It sounds like you have learned something new about the cool changes that take place inside a cocoon! Thanks for visiting us to Wonder! :)

Rainbow Dash

Wonderopolis

Apr 16, 2013

Hey there, Rainbow Dash! Thanks for telling us all about your caterpillar adventure with your dad. We're sorry to hear that none of the caterpillars survived, but we are so happy that you learned all about their lives while you cared for them. Keep up the awesome SCIENCE work! :)

Emma

Apr 15, 2013

Dear Wonderopolis, In my second grade class are studying insects and we each have 2 baby caterpillars. My two are named Jack and Rose. My teacher had four kids last year whose caterpillars died. I hope that mine do not die. My class has them until they turn into butterflies. I learned that a butterfly has to expand its wings before she/he can fly! Your Friend, Emma

Wonderopolis

Apr 14, 2013

Hey there, Emily, we're so glad you are here today! Cocoons are strong enough to keep the caterpillar safe while it changes and grows. Isn't it incredible to learn all about the stages of life before a butterfly can soar in the sky? Thank you for sharing your far-away Wonder guesses- nice work! :)